The effect of short-term acidification during spring snovvmelt on selected Mollusca in south-central Ontario

1986 ◽  
Vol 64 (8) ◽  
pp. 1690-1695 ◽  
Author(s):  
Mark R. Servos ◽  
Gerry L. Mackie
Keyword(s):  
Sulfuric Acid ◽  
Direct Result ◽  
Confounding Factors ◽  
Life Stages ◽  
Short Term ◽  
Recruitment Failure ◽  
South Central ◽  
Survival And Reproduction ◽  
Plastic Lake ◽  
Spring Snowmelt

Limestone and sulfuric acid were used to manipulate the pH of water in three artificial channels in the outflow of Plastic Lake, south-central Ontario, during the spring of 1982. Using artificial channels allowed the manipulation of pH during a natural pH depression (i.e., spring snowmelt) while minimizing confounding factors such as mobilization of metals from aquatic sediments. Addition of sulfuric acid extended and exaggerated the natural pH depression (from pH 5.8 to 4.8) to as low as pH 3.5 over 5 days, while addition of limestone prevented depression of pH below 6.4. Survival and reproduction of the pisidiid clams Pisidium equilaterale Prime and Pisidium casertanum (Poli) and the hydrobiid snail Amnicola limosa Say held in artificial channels were not significantly different (p > 0.05) among treatments. The survival and reproduction of A. limosa was also not affected by exposure to short-term pH depressions (e.g., 5.8 to 4.8; 4.8 to 4.3) in three south-central Ontario streams during spring snowmelt. For various life stages of both P. equilaterale and A. limosa, 96-h LC50 values were below pH 4.0, which was well below the pH observed in any stream in this study. These results suggest that recruitment failure and elimination of A. limosa from acidifying lakes noted in other studies was not a direct result of short-term pH depression during snowmelt.

Reproduction of selected Mollusca in some low alkalinity lakes in south-central Ontario

1985 ◽  
Vol 63 (3) ◽  
pp. 511-515 ◽  
Author(s):  
M. R. Servos ◽  
J. B. Rooke ◽  
G. L. Mackie
Keyword(s):  
Low Ph ◽  
Acidic Lakes ◽  
Recruitment Failure ◽  
South Central ◽  
Summer Growth ◽  
Growth And Reproduction

Growth and reproduction of several species of molluscs were examined in six low alkalinity lakes in south-central Ontario. Amnicola limosa (Gastropoda: Amnicolidae) held through the summer of 1982 in cages in acidic lakes (pH 5.78–5.89) grew slower (p < 0.01) than those held in less acidic lakes (pH 6.03–6.84). The development of eggs of A. limosa in the laboratory was impaired at and below pH 5.0 and delayed at pH 5.5 relative to pH 6.0. Hence the recruitment failure and elimination of A. limosa that has been reported in acidifying lakes may be caused by reduced summer growth and (or) impaired development of the eggs. In contrast, Pisidium spp. (Bivalvia: Pisidiidae) do not appear to be adversely affected by low pH in the lakes in this study (pH 5.78–6.84). Caged Pisidium equilaterale did not have reduced growth in the acidic lakes during the summer of 1982. Pisidium casertanum and Pisidium ferrugineum had only slightly reduced (p < 0.05) fecundity (number of extramarsupial larvae per adult) in acidic lakes relative to less acidic lakes sampled in 1980.

scholarly journals Association Between Past Oral Contraceptive Use and the Prevalence of Hypertension in Postmenopausal Women: The Fifth (2010–2012) Korea National Health and Nutrition Examination Survey (KNHANES V)

2021 ◽  
Author(s):  
JungJu Lee ◽  
Hyunsuk Jeong ◽  
Joo Hee Yoon ◽  
Hyeon Woo Yim
Keyword(s):  
Postmenopausal Women ◽  
National Health ◽  
Contraceptive Use ◽  
Confounding Factors ◽  
Nutrition Examination Survey ◽  
Short Term ◽  
Multivariable Logistic Regression Model ◽  
Cross Sectional ◽  
Health And Nutrition

Abstract Background: There is little evidence as to whether the use of oral contraceptives(OC) during the fertile years affects the development of postmenopausal hypertension. This study aimed to evaluate the effects of past use of OC on the development of hypertension in postmenopausal women. Methods: This was a cross-sectional study conducted using data from the Fifth Korea National Health and Nutrition Examination Survey of postmenopausal women. Subjects were classified into three groups based on past OC use duration: nonusers, short-term users(0–30months), and long-term users(≥30 months). We evaluated the development of hypertension in women after menopause. A multivariable logistic regression model was used to identify the association between the use of OC during the fertile years and the prevalence of hypertension after menopause following adjustment for potential confounding factors. Results: Of the 3,386 postmenopausal women, 2,713 were nonusers of OC, 489 were short-term users, and 184 were long-term users. Women who had used OC for 30 months or more had a significantly greater prevalence of hypertension after menopause than those who had never taken OC. The association between taking OC for 30 months or more during the fertile years and the prevalence of hypertension after menopause was significant following adjustment for potential confounding factors (aOR:1.92; 95%CI:1.22–3.00). Conclusion: This study identified an association between past OC use and an increased prevalence of hypertension in postmenopausal women. Our results suggest that long-term use of OC during the fertile years can be an important risk factor for subsequent hypertension after menopause.

Outcomes

2013 ◽  
pp. 221-226
Author(s):  
David L. Scott
Keyword(s):  
Quality Of Life ◽  
Disease Activity ◽  
Short Form ◽  
Organ Damage ◽  
Confounding Factors ◽  
Short Term ◽  
Self Assessment ◽  
The Matrix ◽  
The Impact

Outcomes evaluate the impact of disease. In rheumatology they span measures of disease activity, end-organ damage, and quality of life. Some outcomes are categorical, such as the presence or absence of remission. Other outcomes involve extended numeric scales such as joint counts, radiographic scores, and quality of life measures. Outcomes can be measured in the short term—weeks and months—or over years and decades. Short-term outcomes, though readily related to treatment, may have less relevance for patients. Clinical trials focus on short-term outcomes whereas observational studies explore longer-term outcomes. The matrix of rheumatic disease outcomes is exemplified by rheumatoid arthritis. Its outcomes span disease activity assessments like joint counts, damage assessed by erosive scores, quality of life evaluated by disease-specific measures like the Health Assessment Questionnaire (HAQ) or generic measures like the Short Form 36 (SF-36), overall assessments like remission, and end result such as joint replacement or death. Outcome measures capture the impact of treating rheumatic diseases. They are influenced by disease severity and effective treatment. They also reflect many confounding factors. These include demographic factors like age, gender, and ethnicity and also deprivation, as poverty worsens outcomes. Comorbidities affect outcomes and patients with multiple comorbid conditions have worse quality of life with poorer outcomes. Patient self-assessment has grown in importance; it is simple and understandable. However, self-assessment can vary over time and does not always reflect assessors’ perspectives. Caution is needed comparing outcomes across units; the various confounding factors and measurement complexities make such comparative analyses challenging.

Do cows regulate diet choice within the short-term time frame of a meal?

2003 ◽  
Vol 2003 ◽  
pp. 6-6
Author(s):  
M. P. Yeates ◽  
B. J. Tolkamp ◽  
I. Kyriazakis
Keyword(s):  
Feeding Behaviour ◽  
Time Frame ◽  
Food Type ◽  
Direct Result ◽  
Diet Choice ◽  
Short Term ◽  
Biological Unit

When cows are offered a choice of foods they are able to select a consistent combination of these foods over long periods of time. Consistent long-term diet choice (DC) is the result of feeding behaviour, which may be regulated in the short-term. The shortest unit of feeding that can be measured is often a visit to a feeder supplying one food type only. These visits are usually clustered into meals, which are the shortest biological unit in which DC can be expressed. Previous work led us to hypothesise that animals may select a consistent diet within meals, thus ensuring nutrient synchronisation in the short-term. Therefore, the aim of this study was to investigate whether long-term average DC was a direct result of cows selecting a consistent diet within meals.

Lake Acidification as a Limiting Factor in the Distribution of the Freshwater Amphipod Hyalella azteca

1986 ◽  
Vol 43 (2) ◽  
pp. 288-292 ◽  
Author(s):  
M. Stephenson ◽  
G. L. Mackie
Keyword(s):  
Surface Water ◽  
Hyalella Azteca ◽  
Lake Acidification ◽  
Limiting Factor ◽  
Short Term ◽  
Natural Surface ◽  
Bioassay Data ◽  
Plastic Lake

The distribution of the freshwater amphipod Hyalella azteca in 79 Ontario lakes suggests that its absence may be a good indicator of lake acidification. Hyalella azteca was present in 69 of 71 nonacidified lakes, and absent in 8 of 8 lakes which either are now ar recently were considered acidified. Bioassay data indicate a 96-h LC50 of pH 4.4 and a 10-d threshold LC50 of pH 4.5 for H. azteca in a natural surface water. Hyalella azteca is extremely rare in Plastic Lake, which undergoes severe short-term acidification in spring, and recruitment is delayed 2 wk in Heeney Lake which undergoes similar short-term acidification, in Dickie, Harp, Red Chalk, and Blue Chalk lakes, where springtime pH depressions below pH 4.7 were not recorded, H. azteca is abundant.

scholarly journals Thermal performance curves reveal shifts in optima, limits and breadth in early life

2020 ◽  
Vol 223 (22) ◽  
pp. jeb233254
Author(s):  
Adriana P. Rebolledo ◽  
Carla M. Sgrò ◽  
Keyne Monro
Keyword(s):  
Embryo Development ◽  
Thermal Performance ◽  
Early Life ◽  
Thermal Sensitivity ◽  
Life Stage ◽  
Life Stages ◽  
Parametric Bootstrapping ◽  
Performance Curves ◽  
Survival And Reproduction ◽  
Mixed Modelling

ABSTRACTUnderstanding thermal performance at life stages that limit persistence is necessary to predict responses to climate change, especially for ectotherms whose fitness (survival and reproduction) depends on environmental temperature. Ectotherms often undergo stage-specific changes in size, complexity and duration that are predicted to modify thermal performance. Yet performance is mostly explored for adults, while performance at earlier stages that typically limit persistence remains poorly understood. Here, we experimentally isolate thermal performance curves at fertilization, embryo development and larval development stages in an aquatic ectotherm whose early planktonic stages (gametes, embryos and larvae) govern adult abundances and dynamics. Unlike previous studies based on short-term exposures, responses with unclear links to fitness or proxies in lieu of explicit curve descriptors (thermal optima, limits and breadth), we measured performance as successful completion of each stage after exposure throughout, and at temperatures that explicitly capture curve descriptors at all stages. Formal comparisons of descriptors using a combination of generalized linear mixed modelling and parametric bootstrapping reveal important differences among life stages. Thermal performance differs significantly from fertilization to embryo development (with thermal optimum declining by ∼2°C, thermal limits shifting inwards by ∼8–10°C and thermal breadth narrowing by ∼10°C), while performance declines independently of temperature thereafter. Our comparisons show that thermal performance at one life stage can misrepresent performance at others, and point to gains in complexity during embryogenesis, rather than subsequent gains in size or duration of exposure, as a key driver of thermal sensitivity in early life.

Omnivory of the larval phantom midge (Chaoborus spp.) and its potential significance for freshwater planktonic food webs

1994 ◽  
Vol 72 (11) ◽  
pp. 2055-2065 ◽  
Author(s):  
Marianne V. Moore ◽  
Norman D. Yan ◽  
Trevor Pawson
Keyword(s):  
Diet Composition ◽  
Trophic Levels ◽  
Potential Significance ◽  
Keratella Cochlearis ◽  
Planktonic Food ◽  
South Central ◽  
Invertebrate Predator ◽  
Asplanchna Priodonta ◽  
Phantom Midge ◽  
Plastic Lake

Developmental and seasonal changes in the preferred prey and the diet composition of the invertebrate predator Chaoborus punctipennis were determined in Plastic Lake, an acidified (pH 5.6) lake in south-central Ontario, Canada. All instars consumed rotifers (mainly Keratella cochlearis, Ploesoma sp., and Asplanchna priodonta), and instars III and IV fed preferentially on crustaceans (mainly bosminids and copepods). Phytoflagellates (Peridinium sp. and Dinobryon sp.), however, numerically dominated the diet of all instars examined (II–IV), and were consumed by instar II larvae in excess of their relative availability. On 40 and 20% of the sampling dates, instars III and IV, respectively, consumed phytoflagellates in accordance with their relative abundance in the lake. Although the contribution of phytoflagellates to the biomass-based diet of C. punctipennis was low, on one occasion phytoflagellates formed almost half of the diet biomass of instar II larvae. A review of the literature shows that in lakes where phytoflagellate densities are high (≥ 100–200/mL), phytoflagellates contribute ≥ 50% of the diet biomass of all instars of Chaoborus spp. These findings indicate that Chaoborus spp. are omnivores that frequently feed on phytoflagellates even when alternative animal prey are abundant. Consumption of phagotrophic phytoflagellates by Chaoborus spp. and other large invertebrate omnivores, such as Mysis spp., Epischura spp., and cyclopoid copepods, may increase the transfer efficiency of organic carbon from the microbial food web to the upper trophic levels in fresh waters. In acidified lakes, consumption of large dinoflagellates by Chaoborus spp. and other invertebrate omnivores may ameliorate the hypothesized bottleneck impeding the flow of carbon between phytoplankton and zooplankton.

scholarly journals Design of fault trees as a practical method for risk analysis of CCS: Application to the different life stages of deep aquifer storage, combining long-term and short-term issues

2011 ◽  
Vol 4 ◽  
pp. 4193-4198 ◽  
Author(s):  
Régis Farret ◽  
Philippe Gombert ◽  
Franz Lahaie ◽  
Auxane Cherkaoui ◽  
Stéphane Lafortune ◽  
...  
Keyword(s):  
Risk Analysis ◽  
Practical Method ◽  
Life Stages ◽  
Short Term ◽  
Deep Aquifer ◽  
Fault Trees ◽  
Aquifer Storage

Long-Term Biological Damage: What is Known, and How Should that Influence Decisions on Response, Assessment, and Restoration?

2001 ◽  
Vol 2001 (1) ◽  
pp. 399-403 ◽  
Author(s):  
Mark G. Carls ◽  
Ron Heintz ◽  
Adam Moles ◽  
Stanley D. Rice ◽  
Jeffrey W. Short
Keyword(s):  
Oil Spill ◽  
Polyaromatic Hydrocarbons ◽  
Environmental Cost ◽  
Life Stages ◽  
Prevention Measures ◽  
Long Term Effects ◽  
Short Term ◽  
Exxon Valdez ◽  
Damage Scenarios

ABSTRACT Immediate damage from an oil spill is usually obvious (oiled birds, oiled shoreline), but long-term damage to either fauna or habitat is more subtle, difficult to measure, difficult to evaluate, and hence often controversial. The question is, are too many of response decisions such as dispersant use or shoreline cleanup based on short-term acute toxicity models? Have long-term damage scenarios been discounted because of the inherent difficulty in deriving definitive answers? Experience with the Exxon Valdez oil spill is shedding new light on the potential for long-term damage. Government-funded studies demonstrated that oil persists in certain habitats for extended periods of time, such as the intertidal reaches of salmon streams, in soft sediments underlying mussel beds, and on cobble beaches armored with large boulders. Observation of long-term persistence of oil in some habitats is not new, but an increasing number of studies indicate that fauna may be chronically and significantly exposed to oil in these habitats. The toxic components in oil responsible for much of the long-term effects are believed to be the larger 3- and 4-ring polyaromatic hydrocarbons (PAHs) that can induce cellular and genetic effects rather than the narcotic monoaromatic hydrocarbons (MAHs) responsible for acute mortalities. Observation of long-term persistence of Exxon Valdez oil, coupled with adverse effects on sensitive life stages, leads to the conclusion that strategies based on minimizing acute mortalities immediately following a spill probably do not provide adequate protection against long-term damage. When making environmental decisions in response to a spill (prevention measures or restoration measures), more weight should probably be given to long-term issues rather than discounting their significance. Total environmental cost is the sum of short-term damage and long-term damage, and long term-damage to habitats and sensitive life stages probably needs more consideration even though it is very difficult to evaluate and compare to the relatively obvious acute issues.

Sign in / Sign up

Export Citation Format

Share Document